The climate of the Redwood Creek basin varies from moderate seasons along the coast to the more extreme seasons common to the higher inland areas. The predominant influence on the climate in the lower basin, extending some ten to twenty miles inland, is moist marine air, which moves inland by prevailing onshore winds. Fog is a dominant climatic feature along the coast, generally occurring daily in the summer and not infrequently throughout the year. This oceanic influence has a greatly moderates the climate of the coastal areas over most of the year. Temperatures in the coastal region of the Redwood Creek basin vary only slightly, with a seasonal difference of only 10–15°F. For example, mean temperatures at Redwood Park are 47°F in January and 59°F in June.
The highest instantaneous peak discharge of record at the Orick gauge occurred in 1965, with a discharge of just above 50,500 cubic feet per second (cfs) (Figure III- 4). Other high peak flows occurred in water years 1956, 1972, and 1975. At the O’Kane gauge (see Appendix G), the highest instantaneous peak discharge of 12,200 cfs occurred in 1975. The record annual minimum seven-day running average low flow at Orick was 2 cfs in 1988. Although, the lower mainstem was dry near the HWY 101 bridge in 2001 and 2002 At the O’Kane gauge, the record low was 1 cfs in 1993.
The Redwood Creek basin is situated in a tectonically active and geologically complex area, with some of the highest rates of uplift, and seismic activity in North America (Cashman et al. 1995, Merritts 1996). Most of the bedrock underlying the basin has been broken and sheared by tectonic action making it relatively weak, easily weathered, and naturally susceptible to landsliding and erosion. Heavy rainfall, high regional uplift rates, seismicity and weak bedrock combined with impacts from land use produce widespread landsliding and high sediment input to streams.
Fluvial geomorphology is the study of stream processes and channel forms. To aid in the assessment of stream processes and stream-habitat quality, the NCWAP geomorphologists mapped stream features from aerial photographs. These included features indicative of disturbance (disturbance-features) associated with erosion and excessive in channel sediment such as widened and multi-thread channels, mid-channel bars, bank erosion, shallow landslides adjacent to channels, and excessive lateral bars. By photo year 2000, there were a greater proportion of more stable features including point bars and vegetated bars which are not considered disturbance features for the analysis.
Vegetation varies over the basin from Sitka spruce, red alder and grasslands in the Estuary Subbasin to old growth redwood forest along the lower portion of the drainage and Douglas-fir, intermixed with oak woodlands and hardwoods, to ponderosa and Jeffery pine stands along the upper elevations. Areas of grasslands are also found along the main ridge tops and south-facing slopes of the basin. Prior to the harvesting of timber within the Redwood Creek basin, 83% (150,000 of 181,000 acres of the drainage) supported mature coniferous forests. The remainder of the basin, approximately 17%, supported grasslands and oak woodlands. Redwood Creek drainage currently supports about 24,000 acres (13% of area) of old-growth coniferous forests. Most of the old growth forest is in publicly owned lands and managed by RNSP. By the year 2000, approximately 87% (130,700 acres) of the total forested area had been logged at least once.
Native Americans made extensive use of Redwood Creek, especially along the main channel of Redwood and Prairie Creeks. Wide-ranging villages were located along the flood plain near the mouth of the ocean. The Yurok People occupied approximately 300,000 acres (Lara 1996) covering the area from the mouth of Little River through the lower portion of Redwood Creek and north to Wilson Creek and inland to Bluff Creek along the Klamath River. Waterman (1923) recorded no fewer that five villages in this area of Redwood Creek during his work on the Yurok Tribe. The rich forests of this region were teeming with wildlife and the streams were full of fish. Fire was also used as a land management tool. Forests were burned on a frequent basis to reduce the fuel loading as an aid to hunting. Although the Yurok People did not cut down redwood trees, a fallen redwood tree or portions of the tree were well utilized. Uses of the redwood tree included: sticks for cooking and drying various fish, for drying meat such as elk or sea lion, construction material for houses or sweat lodges, gill net floats, net needles, drum handles, baby baskets, storage baskets, women’s work dresses, chairs, pillows, and the indispensable canoe. Chilula people inhabited the lower and central portion of Redwood Creek. Chilula villages were located on or near lower Redwood Creek from the inland edge of the redwood belt to a few miles up stream of Minor Creek. Eighteen village sites were recorded as belonging to these people. All but one of these sites was located on the eastern side of the creek (Kroeber 1976) in order to take advantage of the of the increased sunlight. A third group of Native Americans that inhabited Redwood Creek were the Whilkut people. They occupied upper Redwood Creek area upstream of the Chilula to the headwaters and portions of the Mad River and Grouse Creek drainages.
European settlement of the Orick area was first recorded in the 1850s. During January 1851, a small gold rush broke out over the beach sand at Gold Bluff. Miners, seeking to develop the area north of Redwood Creek, in the area of the “bluffs” and Majors Creek, first settled here. The alluvial plain in and around Orick was cleared of the extensive Sitka spruce stands, hardwood trees, and thick brush and was converted to farm and grazing land. This converted area accounts for less than one percent of the total basin area. The upper areas of Redwood Creek were becoming utilized and populated during this same time period by miners and settlers. The initial use of hardwoods in this area was for fuel wood, fence posts, and tanbark. Bark from the tanoak tree, was used for the tanning of hides.
Historic cattle ranching and sheep farming utilized the native meadows, grasslands, and oak woodlands. Cattle were moved into the Redwood Creek area and by 1860 extensive herds were located along the Bald Hills and Upper Redwood Valley. After 1865 the sheep and wool industry became the leading agricultural enterprise in the eastern portion of the valley, away from the dense stands of timber. Excellent stands of native grasses provided year-round grazing and were well suited for sheep grazing. Wool produced in this area of Humboldt County was considered to be the best grown on the Pacific Coast and brought the highest prices on the open market (Green 1980).
Prior to 1968 most of the Redwood Creek drainage was held in private ownership. Timber companies or large family ranches owned most of this land base. During this time timber harvesting was the dominant land use. In the early 1920s, the Save-the-Redwoods League purchased approximately 14,000 acres, creating a sanctuary of old growth coast redwood in the Prairie Creek basin which became part of the Redwood State Park system. Redwood National Park was created in 1968. Ten years later Congress added more land that included logged-over portions of Redwood Creek in the Lower Subbasin. Timber production was no longer the principal land use in the lower part of the drainage. Recreation and preservation of natural resource values became the main management goals in the park lands.
Currently, 43 percent of the basin is within public ownership. Privately held lands account for 56 percent of the ownership (101,142 acres) within the Redwood Creek basin. The Redwood Creek Landowners Association is comprised of ten private ownerships (Landowners Association 2000) ranging from small to large industrial tracts, which own and manage lands within Redwood Creek. This collective ownership accounts for more that 80% of the privately owned property in the basin. Eight large ownerships of larger than 3,000 acres each account for 90% of this total. Some of these members have managed land within the basin for fifty years or longer. These landowners conduct a mix of land uses, including ranching and timber management.
Timber harvest has been the dominant land use in the private lands of the Redwood Creek basin. Initial timber harvests are visible on the 1942 aerial photos. This early logging was conducted with steam donkeys and cable systems as evident from the telltale yarding patterns in the photos. Some early tractor logging started in the late 1930s, but it did not become highly utilized until after World War II. The post-war years and associated housing boom created an increase in the demand for Douglas-fir logs. This boom led to an increase in logging within the middle and upper portions of Redwood Creek. During the period from 1949 to 1954, 19 percent of the area was logged (Best 1984). The harvest practices of this era resulted in a significant amount of area that grew back in extensive tanoak stands, which are present. These almost pure tanoak stands, which have a low to negative harvest value depending upon highly variable wood chip markets, are being harvested and utilized on an experimental basis. Once the stands are cut, the areas are replanted to native Douglas-fir to reestablish high-timber-value tree species.
By 1948, five percent of the Redwood Creek basin (excluding Prairie Creek Subbasin) had been harvested. The most active period of harvesting was between 1962 and 1978, when 32% of the basin was harvested in 16 years. By 1978, 81% (approximately 121,000 acres) of the coniferous forests of the basin had been logged and approximately 1,240 miles of roads and 5,600 miles of skid trails were constructed to remove timber from the forest (Best 1995). Much of this work was done prior to rules of the Forest Practice Act of 1973.
By the year 2000, an estimated total of 130,680 acres (72% of the landscape or 87% of the coniferous forest) within the Redwood Creek basin has been cut on a first entry harvest basis. An additional 30,000 acres in the Middle and Upper subbasins have undergone a second or third entry harvest. Table I shows the cumulative area of timber harvesting within the Redwood Creek Basin.
Cumulative first entry harvest in the Redwood Creek Basin
There are approximately 2,000 miles of roads within Redwood Creek basin. Redwood National Park has estimated that about 50 miles of roads are located within the inner gorge of watercourses. Only major highways and most county roads are paved. The remainder of the roads within the drainage are surfaced with either native material, gravel or rock from a local source.
The vast majority of the roads in the basin were constructed during the initial timber harvest period of the 1950s. Most private road construction was for the purpose of timber harvesting. This road system was identified as a major source of sediment delivered to stream channels. With evolving changes in Forest Practice Regulations since the early 1970s, new harvest-related road construction has had to meet increasingly higher standards. These regulations cover construction activities such as operations on steep slopes, road alignment, road grades, erosion control, watercourse crossings, culvert instillation, winter period operations, and road maintenance. New construction undertaken by Caltrans for a new freeway by-pass accounted for elevated amounts of runoff and sediment production by the time the project was finished in 1992. Impacts of particular concern occurred during a heavy rainstorm in October 1989.
Water Column Chemistry
In general, the existing thirty years of water chemistry data characterizes Redwood Creek as a moderately hard water, moderately oligotrophic stream, with adequate water quality to support salmonid populations. The data are within optimal ranges defined as Basin Plan objectives. Nothing can be concluded about the quality of water from the upper portion of the basin due to a lack of sampling sites, except that water quality in the mainstem (near the confluence with Minon Creek) is good. Dissolved oxygen and pH values do not change much from one subbasin to another. Conductivity in Prairie Creek was slightly lower in the 1970s compared with the rest of the basin. Nutrients (nitrogen and phosphorus) in the basin are low.
Two metrics were used to evaluate summer water temperature suitability for salmonids of Redwood Creek. The first metric is the maximum weekly average temperature (MWAT), which is the upper temperature recommended for a species life stage or a threshold that should not be exceeded over any seven-day period (Armour 1991). The second metric is the seasonal maximum or the highest temperature observed during the hottest part of the year. Seasonal maximum or peak temperature data indicate temporary or short-term exposure to extreme conditions. It is generally accepted that a threshold temperature exists that fish can withstand for short consecutive period of hours before damage is caused by stress (Armour 1991). The instantaneous seasonal maximum that may lead to salmonid lethality is >75°F (RWQCB 2000).
For sites throughout the basin, the MWATs calculated from continuous summer temperature data from 1994 to 2001 are borderline or exceed the “fully suitable” range for optimal salmonid production (Table III- 29 and Figure III- 29). Temperatures in Redwood Creek basin show maximum MWATs for the period of record along the mainstem ranging from 67-72º F and tributaries in the 54-68º F range. It is interesting to note that the MWAT was reached during the same week across the basin. Temperature data from 1974 in Woods (1975) lists three tributaries (Lost Man, Little Lost Man, and Panther Creeks) with MWATs ranging from 57-64ºF. These measurements were taken with less accurate continuous recording equipment compared to those in use today. The data from 1974 should be considered as descriptive and are included to illustrate the complete record of temperature data gathered for Redwood Creek. However, the stream may have been more exposed to sunlight because of removal of shade canopy during timber harvests giving validity to the high temperature of Lost Man Creek in 1974.
The mainstem reaches, especially in the Upper and Middle subbasins, experience the highest MWAT temperatures perhaps due to wide aggraded channels with little to no canopy cover and a NW/SE aspect. Throughout the basin, cold water tributaries help to ameliorate increases in, and in some cases, lower mainstem temperatures. Overall, the headwaters area of Redwood Creek and Prairie Creek subbasin are the coolest perhaps due to cold water inputs from tributaries with tall streamside trees and steep inner gorges which provide shading over the channel.
In-channel sediment is particularly important to examine for Redwood Creek since the basin is listed as sediment impaired under Section 303(d) of the federal Clean Water Act, and hence falls under jurisdiction of the state and federal TMDL programs. Data for sediment in the Redwood Creek basin are available from the RNSP and USGS for pebble counts, sediment cores, and suspended sediment at stream gauges since 1973. See Appendix C for sediment sampling locations and data from all sources. RNSP and USGS conducted pebble count surveys and calculated D50 values at four sites on mainstem Redwood Creek from 1979 to 1995 (Figure III- 32). These values are directly comparable to the US EPA minimum target for D50 at >37mm. The data are plotted in by site and year. Particle size distribution data from pebble counts used to calculate the D50 are in Tables 10-14 in Appendix C. Mainstem Redwood Creek did not meet the mean particle size target considered suitable for salmonid habitat at the confluence with Miller and Harry Weir creeks for the period monitored. Initially particle size met TMDL targets at Lupton Creek, but did not after 1981. Mean particle sizes increased over the study period to suitable levels in Redwood Creek at the confluence with Panther Creek.
Suspended Sediments and Turbidity
High turbidity levels in Redwood Creek are believed to occur more frequently and persist longer than in the past. Chronic turbidity and elevated levels of suspended sediments affect the ability of sight-oriented juvenile salmonids to locate food and may cause gill abrasions. A suppressed feeding ability may reduce the growth rate of juvenile fish and impair completion of successful smoltification and ultimately reduce survival rates upon entering the sea. Chronic turbidity may also reduce the reproductive cycle and growth of some aquatic invertebrates that serve as prey species for anadromous salmonids
It was shown that land use is responsible for increases in suspended sediment concentrations in managed areas within the Redwood Creek basin (Nolan and Janda 1995). Nolan and Janda (1995) found that suspended sediment discharge was roughly ten times greater from timber harvested terrain compared to unharvested terrain. Additionally, Klein (2001) found that the number of consecutive days that exceeded a turbidity target of 27 mg/l was four to five times greater in planning watersheds managed for timber harvest ( Panther and Lacks creeks) when compared to unmanaged planning watersheds (Prairie and Little Lost Man creeks). While some of the differences may be explained by inherent sediment producing characteristics between the planning watersheds, the main factor for the higher turbidity levels in Lacks and Panther creeks is likely due to timber harvest and related management activities (Klein 2001).
Fishery resources of the Redwood Creek Basin
Redwood Creek basin supports anadromous populations of fall run Chinook salmon (Oncorhynchus tshawytscha), coho salmon (O. kisutch), winter and summer runs of steelhead trout (O. mykiss), coast cutthroat trout (O. clarki clarki), and other valuable fisheries resources (Table 1). Although a recent estimate of the size of anadromous salmonid populations of the Redwood Creek basin has yet to be determined, a review of past fisheries studies, anecdotal information and data collected for this assessment indicates that the present populations are less abundant and less widely distributed compared to their historic presence (Hallock et al. 1952; Briggs 1953; USFWS 1960; Anderson 1988; Brown 1988; Busby et al. 1994; Van Kirk 1994; McEwan and Jackson 1996; NMFS 1998; McElhany et al. 2000; CDFG 2002).
There are approximately 125 miles of stream habitat accessible to anadromous salmonid in the Redwood Creek basin. The mainstem Redwood Creek provides approximately 65 miles and tributaries provide approximately 60 miles of stream of accessible habitat.
Streams in the Prairie Creek Subbasin provide anadromous salmonids the largest amount of tributary habitat of all the subbasins. The remainder of anadromous fish bearing tributary habitat is distributed between approximately 46 named tributary streams located in the Lower, Middle and Upper subbasins (Brown 1988). The steep channel gradient restricts access to only the lower reaches of most tributary streams in the Lower, Middle and Upper subbasins. The majority of suitable tributary habitat is found in only ten streams including Bridge, Emerald, and Tom McDonald creeks of the Lower Subbasin, Lacks, Minor, Coyote, Panther, and Wiregrass creeks of the Middle Subbasin, and Minon and Bradford creeks of the Upper Subbasin. Other tributary streams are still important as they cumulatively provide important habitat for anadromous populations and also contribute important water flows into Redwood Creek. In addition, resident populations of rainbow and coastal cutthroat trout exist in many tributaries above barriers to anadromous salmonids.
From the long-term perspective, anadromous salmonids of Redwood Creek, show declines from historic numbers and in distribution across the basin. In 1960, the U.S. Fish and Wildlife Service estimated spawner escapement of 5,000 Chinook, 2,000 coho, and 10,000 steelhead (USFWS 1960). These estimates were made based on data collected from other streams and applied to Redwood Creek. They were meant to provide a general magnitude of anadromous salmonid runs are not indicative of larger runs of prior years (USFWS 1960; CDFG 1965; and RNSP 2000) The data needed to determine if populations are continuing to decline, have stabilized, or are on the rise across the basin are not available.
The decline in anadromous salmonids populations is not unique to Redwood Creek. For example, in 1984-85 the statewide total of natural coho salmon spawners was estimated at 6 to 15% of the level of the 1940s (CDFG 2002). In addition, coho and Chinook populations drastically declined in the Eel River according to adult salmon counts at Benbow Dam, South Fork Eel River (CDFG 2002).
In response to California’s declining wild populations, Chinook, coho, and steelhead are listed as “threatened” under the Federal Endangered Species Act (FESA). In 2002, the California Fish and Game Commission found that North Coast coho salmon warranted listing as threatened, as defined under the California Endangered Species Act (CESA). In addition, several other plant and animal species living in the Redwood Creek basin receive special status protection under the FESA and CESA including coastal cutthroat trout, which is considered a California species of special concern by the Department of Fish and Game (Appendix D).
Freshwater and estuarine habitat degradation and has been identified as a leading factor in the decline of Redwood Creek’s anadromous salmonids (Ricks 1982; Larson 1982; Hofstra 1983; Anderson 1988; Brown 1988; Madej 1991; and CDF&G 2002). Widespread declines of summer steelhead, sea run coastal cutthroat, coho and Chinook salmon is likely linked to their sensitivity to degradation of specific habitat components necessary to complete the freshwater and/or estuarine phase of their life cycle. Because steelhead tolerate a wider range of habitat conditions than the other anadromous species, they are more widely distributed in the basin and have persisted in streams where other species have declined or are now rarely observed.
Similar to most north coast streams, there has been neither basin-wide quantitative assessment nor coordinated long term monitoring of all Redwood Creek’s anadromous salmonid stocks. There are recent population data such as downstream migrant studies and spawning surveys available for select streams. However these data are inconclusive because they lack of consistent effort across the study areas, or have not been ongoing for sufficient time to establish trends, and may require optimal environmental conditions to conduct observations. Coordinated studies such as downstream migrant trapping, spawner surveys, and other population assessment techniques may soon provide the level of information needed to make quantitative assessments of the current status and trends of Redwood Creek’s anadromous salmonid populations.